Which preventive scan is right for you?
The preventive scan with the strongest evidence depends on your age, sex and risk factors, not on which scan sees the most. Guideline bodies recommend low-dose lung CT for heavy current and former smokers aged 50 to 80, bone density testing for women 65 and older, an abdominal aortic ultrasound for men 65 to 75 who have ever smoked, and a coronary calcium scan when a statin decision is uncertain. Whole-body MRI and multi-cancer blood tests are not recommended by any major guideline body for people without symptoms, although they are sold to them. The table compares all twelve.
| Scan | Looks for | Radiation | Time | Guideline-backed for |
|---|---|---|---|---|
| Full-body MRIMRI | A non-contrast, radiation-free MRI survey from head to upper thighs that looks for unsuspected tumors, aneurysms and organ disease. Finds something in about 95% of people and a confirmed cancer in about 1%. Not recommended by the ACR for people without symptoms or risk factors. | None | 22 to 75 minutes in the scanner depending on protocol; about 1 to 1.5 hours on site | People with hereditary cancer syndromes under specialist surveillance; not recommended for asymptomatic adults by the ACR or CAR |
| Brain MRIMRI | A radiation-free look at the brain and its arteries for aneurysms, tumors, silent strokes and white-matter change. Incidental findings turn up in about 1 in 37 scans, most of them harmless. No guideline body recommends it for people without symptoms. | None | 30 to 60 minutes; about 15 to 25 minutes for abbreviated screening protocols | Symptoms such as red-flag headache, seizures, neurological deficits or suspected tumor; not recommended as a screening test |
| Coronary calcium CTCT | A fast, non-contrast CT that measures calcified plaque in the coronary arteries and reports an Agatston score. The ACC/AHA say it is reasonable when a statin decision is uncertain; a score of zero is the strongest known marker of low risk. | Low: about 1.7 mSv, roughly 6 months of background radiation | Under 20 minutes; the scan itself takes seconds | Adults 40 to 75 at intermediate or borderline 10-year risk when a statin decision is uncertain (ACC/AHA Class IIa) |
| Low-dose lung CTCT | Annual screening for adults 50 to 80 with a 20 pack-year smoking history. The only imaging test proven in randomized trials to cut lung cancer deaths, by 20% in the National Lung Screening Trial. | Low: about 1.5 mSv, roughly 6 months of background radiation | About 15 minutes; the scan itself under a minute | Adults 50 to 80 with 20 or more pack-years who smoke or quit within 15 years, yearly (USPSTF Grade B) |
| Cardiac MRIMRI | The reference standard for heart structure and function: chamber volumes, ejection fraction, valve flow and scar in the muscle, with no radiation. A diagnostic test for symptoms and known disease, not a guideline-backed screen; it does not image the coronary arteries well. | None | 30 to 90 minutes; about 45 minutes on average | Symptoms, abnormal echo or ECG, suspected cardiomyopathy, myocarditis or scar, and known heart disease. Not a screening test. |
| CT angiographyCT | Contrast CT that shows the coronary arteries themselves: soft and calcified plaque and how narrowed each vessel is, graded CAD-RADS 0 to 5. A Class I test for people with chest pain; not a guideline-recommended screen for people without symptoms. | Moderate: listed at 8.7 mSv, often 2 to 4 mSv on modern scanners | 20 to 60 minutes in the room; 1 to 2 minutes in the scanner | People with chest pain at intermediate or higher risk and no known coronary disease (AHA/ACC Class I). Not a screening test. |
| DEXA scanX-ray | Measures bone mineral density at the hip and spine to diagnose osteoporosis, and can measure body fat and lean mass. The lowest-dose X-ray test in medicine. | Very low: 0.001 mSv (spine and hip) to 0.003 mSv (whole body) | 10 to 30 minutes for a spine-and-hip scan; about 7 to 12 minutes for body composition | Women 65+, postmenopausal women under 65 at increased risk (USPSTF Grade B); men 70+ (ISCD) |
| Abdominal ultrasoundUltrasound | Radiation-free imaging of the liver, gallbladder, pancreas, spleen, kidneys and aorta. Includes the one-time abdominal aortic aneurysm check guidelines recommend for older men who have smoked. | None | About 30 minutes | Aortic aneurysm screening: men 65 to 75 who have ever smoked (USPSTF Grade B) |
| Thyroid ultrasoundUltrasound | A radiation-free look at the thyroid for nodules, cysts and goiter, graded by the ACR TI-RADS system. Best used to evaluate a known lump or abnormal blood test rather than as routine screening, which the USPSTF advises against. | None | About 30 minutes | Evaluating a known neck lump, abnormal thyroid labs or a nodule seen on other imaging; not recommended as routine screening (USPSTF Grade D) |
| Skin cancer screeningPhysical exam | A head-to-toe skin exam by a dermatologist with a dermatoscope for melanoma, basal and squamous cell cancers. Melanoma caught while localized has a 5-year survival over 99%; the USPSTF rates population screening "insufficient evidence", not against. | None | 10 to 15 minutes if nothing suspicious is found | Adults with many or atypical moles, fair or sun-damaged skin, a personal or family history of melanoma, tanning-bed use or an organ transplant; evidence insufficient for everyone else (USPSTF Grade I) |
| Comprehensive blood panelBlood test | Dozens of biomarkers from one draw: lipids with ApoB and Lp(a), HbA1c and fasting insulin, hs-CRP, liver, kidney, thyroid, blood count, ferritin and vitamin D. Screening and tracking, not diagnosis; some markers carry strong guideline support and others none. | None | Blood draw under 5 minutes; 1 to 2 tubes | Adults 35 to 70 who are overweight (diabetes screening, USPSTF Grade B); adults 40 to 75 weighing a statin; every adult once for Lp(a) (NLA) |
| Multi-cancer blood testBlood test | One blood draw screened for a DNA methylation signal shared by more than 50 cancer types. Very few false positives, but it misses most stage I cancers and the only randomized trial did not cut late-stage diagnoses. Not FDA approved and not in any guideline. | None for the test; follow-up imaging after a positive usually involves CT or PET | Blood draw of about 20 mL in two tubes, under 5 minutes | GRAIL’s label: adults 50 and older or at elevated cancer risk, alongside standard screening. No guideline body recommends it. Not for pregnancy, age 21 and under, or active cancer treatment. |